Frequencies for first 10,000 rows of haz_id variable in vehicle dataset :

  Hazardous |
  Materials |
Involvement |
  /Placard- |
        HM3 |
Identificat |
 ion Number |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,984       99.84       99.84
         88 |          1        0.01       99.85
       1073 |          2        0.02       99.87
       1203 |          7        0.07       99.94
       1267 |          1        0.01       99.95
       1977 |          1        0.01       99.96
       1993 |          1        0.01       99.97
       8888 |          3        0.03      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 18 Apr 2016